Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study shows: Vast landmasses already existed 2,700 million years ago

15.01.2014
Today, 71% of the earth’s surface is covered by oceans and 29% by land. The question, however, when vast landmasses rose above sea-level is still subject to debate among scientists.

A new study by Jacobs University Bremen, in close cooperation with the University of Bonn and the University of Cologne, shows that 2,700 million years ago vast landmasses already existed on earth. The research results have now been published in science journal Geology. (DOI: 10.1130/G35014.1).


The Temagami Iron Formation: an archive of 2,700-million-year-old seawater
Copyright: M. Bau / Jacobs University Bremen

The question when vast landmasses rose above sea-level remains an issue of debate within the science community. Computer simulations, for example, suggested that 2,500 million years ago only 3% of the Earth’s surface area was dry.

A new geochemical approach to address this issue has now been developed by Michael Bau, Professor of Geosciences at Jacobs University Bremen, his Ph.D. student Sebastian Viehmann and collaborators Dr. Elis Hoffmann (University of Bonn) and Prof. Carsten Münker (University of Cologne), who studied the distribution of rare trace elements and the isotopic composition of hafnium (Hf) and neodymium (Nd) in ancient seawater.

Analyzing unusually pure iron-rich sedimentary rocks (banded iron-formation, BIF) from Temagami, Canada, which are an archive of 2,700-million-year-old seawater, the researchers were able to extend the Hf isotope record of seawater back in time to the Early Earth’s ocean.

The Temagami BIF shows that 2,700 million years ago, seawater was anomalously enriched in the radiogenic Hf-176 isotope, whereas its Nd isotopic composition was normal. This reveals that the same decoupling of Hf and Nd isotopes, which is observed in the modern ocean, did already persist 2,700 million years ago.

Prof. Bau explains: “Seawater that is enriched in Hf-176 is produced when rocks at the Earth’s surface are subjected to terrestrial erosion and weathering. The observed decoupling of Hf and Nd isotopes recorded in the Temagami BIF indicates that already 2,700 million years ago, large areas of dry land were emerged above sea-level and exposed to wind and rain.”

The results of this study are now published in scientific journal Geology.

Decoupled Hf-Nd isotopes in Neoarchean seawater reveal weathering of emerged continents

Authors: Sebastian Viehmann, J. Elis Hoffmann, Carsten Münker, Michael Bau

Contact:
Michael Bau | Professor of Geosciences
Tel.: +49 421 200-3564 | Email: m.bau@jacobs-university.de
Weitere Informationen:
http://geology.gsapubs.org/content/early/2013/12/12/G35014.1.abstract

Andrea Daschner | idw
Further information:
http://www.jacobs-university.de

More articles from Earth Sciences:

nachricht Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle
23.07.2018 | University of Kansas

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Enabling technology in cell-based therapies: Scale-up, scale-out or program in-place

23.07.2018 | Health and Medicine

Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle

23.07.2018 | Earth Sciences

The Maturation Pattern of the Hippocampus Drives Human Memory Deve

23.07.2018 | Science Education

VideoLinks
Science & Research
Overview of more VideoLinks >>>